PURPOSE: To detect the working end point accurately and in-process by detecting the end point of polishing based on the temperature variation on the acting surface of polishing resulting from variation in friction heat generation mode of a work being polished.

CONSTITUTION: A work to be polished vacuum-chucked on an upper surface plate 19 is brought into contact with a polishing cloth 17 stuck on a lower surface plate 16, the upper and lower surface plates 19 and 16 are rotated by a machining control mechanism 21 in R2 and R1 directions, respectively, and working liquid L is sprayed from a nozzle 22 for polishing. The surface temperature of the work to be polished increased due to polishing is detected with a radiation temperature sensor 24 as the surface temperature of the polishing cloth 17. The detected signal SA is inputted into a calculation processing part 26 through an amplifier 25. The calculation processing part 26 calculates a differential factor of surface temperature to polishing time. Using a correlation drawing showing a preset differential factor and polishing time, the advancement of polishing is judged, and the end of polishing is judged. Then the working control mechanism 21 outputs rotation stop signals SSU and SSD to stop the upper and lower surface plates 19 and 16.